← Vulnerability feed

Vulnerability record · CVE-2026-78689 · published 2 September 2026

CVE-2026-78689: Heap-based buffer overflow vulnerability

Description NGINX JavaScript (njs) has a vulnerability in the XML module's namespace prefix list parser, reachable through the xml.exclusiveC14n() method. An unauthenticated remote attacker can trigger it when an affected NGINX configuration passes an externally controlled XML namespace prefix list to that method. Both the njs and the QuickJS (qjs) engines are affected. A crafted prefix list causes an out-of-bounds write past the end of a heap allocation. With the njs engine, which is the engine used when the js_engine directive is absent, this corrupts adjacent objects and crashes the NGINX worker. With the QuickJS engine, the same call additionally leaks the prefix list on every invocation, causing worker memory to grow across requests. The official nginxinc/nginx-saml reference implementation is affected during SAML signature verification. It reads InclusiveNamespaces/@PrefixList from an untrusted SAML message and passes it to xml.exclusiveC14n() before the signature has been verified, so a valid SAML signature is not required. A crafted SAML Response, Assertion, LogoutRequest, or LogoutResponse is sufficient. Code execution has not been demonstrated and cannot be ruled out for all platforms, as the effect of the out-of-bounds write depends on conditions beyond the attacker's control.   Impact This vulnerability allows remote attackers to cause a denial of service on the NGINX system, either through repeatable worker restarts or through worker memory growth or possibly trigger code execution. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

9.2 CVSS 4.0 Critical EPSS 0.76% · top 46.5% CWE-122 · Heap-based buffer overflow Awaiting Analysis
9.2CVSS 4.0 base score
0.76%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
1References
3 Sep 2026Last modified by NVD

Description

Description NGINX JavaScript (njs) has a vulnerability in the XML module's namespace prefix list parser, reachable through the xml.exclusiveC14n() method. An unauthenticated remote attacker can trigger it when an affected NGINX configuration passes an externally controlled XML namespace prefix list to that method. Both the njs and the QuickJS (qjs) engines are affected. A crafted prefix list causes an out-of-bounds write past the end of a heap allocation. With the njs engine, which is the engine used when the js_engine directive is absent, this corrupts adjacent objects and crashes the NGINX worker. With the QuickJS engine, the same call additionally leaks the prefix list on every invocation, causing worker memory to grow across requests. The official nginxinc/nginx-saml reference implementation is affected during SAML signature verification. It reads InclusiveNamespaces/@PrefixList from an untrusted SAML message and passes it to xml.exclusiveC14n() before the signature has been verified, so a valid SAML signature is not required. A crafted SAML Response, Assertion, LogoutRequest, or LogoutResponse is sufficient. Code execution has not been demonstrated and cannot be ruled out for all platforms, as the effect of the out-of-bounds write depends on conditions beyond the attacker's control.   Impact This vulnerability allows remote attackers to cause a denial of service on the NGINX system, either through repeatable worker restarts or through worker memory growth or possibly trigger code execution. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://my.f5.com/manage/s/article/K000162602

Track CVE-2026-78689 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.3CVE-2026-94127F5 big-ip access policy manager heap-based buffer overflow vulnerabilityWhen a BIG-IP APM access policy and an OAuth profile are configured on a virtual server, specific malicious traffic can lead to remote code execution…KEVEPSS 2.2%9.8CVE-2025-25249Fortinet FortiOS and FortiSwitchManager heap buffer overflow via crafted packetsA heap-based buffer overflow (CWE-122/CWE-787) in Fortinet FortiOS 6.4 through 7.6.3 and FortiSwitchManager 7.0 through 7.2.6 lets an unauthenticated…KEVEPSS 3.9%analysed7.8CVE-2026-85880Windows ALPC heap buffer overflow allows local privilege escalationA heap-based buffer overflow in the Windows ALPC subsystem, combined with use of an uninitialized resource, lets an attacker with existing local acce…KEVEPSS 3.6%analysed7.8CVE-2026-53362Linux kernel IPv6 UDP paged allocation out-of-bounds write__ip6_append_data() in the Linux kernel mis-accounts fraggap on the paged-allocation path, leaving the linear skb area undersized while pagedlen is o…KEVEPSS 0.71%analysed7.8CVE-2026-56155Microsoft AD FS access control flaw allows local privilege elevationActive Directory Federation Services (AD FS) on multiple Windows client and server versions has insufficient granularity in its access control, letti…KEVEPSS 0.35%analysed8.8CVE-2009-3459Adobe Reader and Acrobat heap buffer overflow via crafted PDFAdobe Reader and Acrobat 7.x before 7.1.4, 8.x before 8.1.7, and 9.x before 9.2 contain a heap-based buffer overflow (CWE-122) triggered by a crafted…KEVEPSS 87%analysed7.8CVE-2026-33825Microsoft Defender Antimalware Platform access control flaw allows local privilege escalationMicrosoft Defender Antimalware Platform has insufficient granularity of access control (CWE-1220), letting an authorized local attacker elevate privi…KEVEPSS 0.40%analysed9.8CVE-2025-31201Apple OS Pointer Authentication bypass via arbitrary read/writeApple removed vulnerable code that allowed an attacker holding arbitrary read and write capability to bypass Pointer Authentication across iOS, iPadO…KEVEPSS 14%analysed

Source: NIST National Vulnerability Database (record CVE-2026-78689), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.